The Trace-Command cmdlet configures and starts a trace of the specified expression or command. It works like Set-TraceSource, except that it applies only to the specified command.

Parameters

-ArgumentList [<Object[]>]

Specifies the parameters and parameter values for the command being traced. The alias for ArgumentList is Args. This feature is especially useful for debugging dynamic parameters.

-Command <String>

This value isrequired

Specifies a command that is being processed during the trace.

-Debugger [<SwitchParameter>]

Indicates that the cmdlet sends the trace output to the debugger. You can view the output in any user-mode or kernel mode debugger or in Visual Studio. This parameter also selects the default trace listener.

-Expression <ScriptBlock>

This value isrequired

Specifies the expression that is being processed during the trace. Enclose the expression in braces ({}).

-FilePath [<String>]

Specifies a file that the cmdlet sends the trace output to. This parameter also selects the file trace listener.

-Force [<SwitchParameter>]

Allows the cmdlet to append trace information to a read-only file. Used with the FilePath parameter. Even using the Force parameter, the cmdlet cannot override security restrictions.

To specify multiple options, separate them with commas, but with no spaces, and enclose them in quotation marks, such as “ProcessID,ThreadID”.

-Name <String[]>

This value isrequired

Specifies an array of Windows PowerShell components that are traced. Enter the name of the trace source of each component. Wildcards are permitted. To find the trace sources on your computer, type Get-TraceSource.

-Option [<PSTraceSourceOptions>]

Specifies the type of events that are traced. The acceptable values for this parameter are:

Examples

This command starts a trace of metadata processing, parameter binding, and cmdlet creation and destruction of the Get-Process Notepad expression. It uses the Name parameter to specify the trace sources, the Expression parameter to specify the command, and the PSHost parameter to send the output to the console. Because it does not specify any tracing options or listener options, the command uses the defaults–All for the tracing options, and None for the listener options.

These commands trace the actions of the ParameterBinding operations of Windows PowerShell while it processes a Get-Alias expression that takes input from the pipeline.

In Trace-Command, the InputObject parameter passes an object to the expression that is being processed during the trace.

The first command stores the string “i*” in the $A variable. The second command uses the Trace-Command cmdlet with the ParameterBinding trace source. The PSHost parameter sends the output to the console.

The expression being processed is Get-Alias $Input, where the $Input variable is associated with the InputObject parameter. The InputObject parameter passes the variable $A to the expression. In effect, the command being processed during the trace is Get-Alias -InputObject $A” or “$A | Get-Alias.

Additional Notes

Tracing is a method that developers use to debug and refine programs. When tracing, the program generates
detailed messages about each step in its internal processing.
The Windows PowerShell tracing cmdlets are designed to help Windows PowerShell developers, but they are
available to all users. They let you monitor nearly every aspect of the functionality of the shell.
To find the Windows PowerShell components that are enabled for tracing, type Get-Help Get-TraceSource.
A trace source is the part of each Windows PowerShell component that manages tracing and generates trace
messages for the component. To trace a component, you identify its trace source.
A trace listener receives the output of the trace and displays it to the user. You can elect to send the trace
data to a user-mode or kernel-mode debugger, to the host or console, to a file, or to a custom listener
derived from the System.Diagnostics.TraceListener class.
When you use the commandSet parameter set, Windows PowerShell processes the command just as it would be
processed in a pipeline. For example, command discovery is not repeated for each incoming object.
The names of the Name, Expression, Option, and Command parameters are optional. If you omit the parameter
names, the unnamed parameter values must appear in this order: Name, Expression, Option or Name, Command,
Option. If you include the parameter names, the parameters can appear in any order.